Considerable empirical support has been established in recent years for outpatient treatments for adolescent substance use disorders. In particular, strong evidence has been found for the efficacy of family therapy in reducing drug abuse and associated problems. Unfortunately, relapse is a critical problem, with treatment outcome studies showing that fewer than half of treated adolescents remain drug or alcohol free up to one year after treatment. Some evidence suggests that participation in aftercare can reduce the risk of relapse among drug abusing adolescents. No research exists, however, on whether the beneficial effects of family therapy can be made more durable by the addition of an aftercare component. The primary purpose of the proposed Stage I treatment development study is to investigate transitional aftercare interventions designed to supplement family therapy, thereby enhancing the long-term effects of treatment on adolescent substance abuse. The family-based treatment literature indicates that traditional family therapy augmented with multi-systemic ecologically focused intervention components is successful in producing significant outcomes that endure at least12 months posttreatment. Yet, ecologically focused family-based interventions, because of their complex and intensive nature, have proven difficult to implement in naturalistic clinical settings. Group interventions that combine the effectiveness of cognitive behavioral strategies such as coping, drug-refusal, mood management, and communication skills with the benefits of peer social support to motivate continued reductions in substance use represent a promising alternative. The proposed study will examine a group and an ecologically focused intervention, in relation to a third minimal transitional intervention in which phone contacts with families every other week will serve to reinforce family therapy gains. Stage IA will primarily involve refining and initially testing the three manualized interventions. Stage IB will formally pilot test the developed versions of the interventions with 90 substance abusing adolescents and their families. Participants will receive an initial 12-week course of Functional Family Therapy, an established treatment for adolescent problem behaviors. Families will then be randomly assigned (30 per condition) to one of the three 8-week aftercare conditions, the skills-based group, family-based systemic, or minimal transitional interventions. Treatment retention and drug use will be used as measures of outcome to demonstrate the potential promise of the interventions. A few key mechanisms of action associated with the different transitional interventions will also be examined.